AbstractThe age at which female mice attain puberty depends to a large extent on their prior experience with male stimuli. Females exposed to male odors mature more rapidly than those denied access to the smell of a male. Such an odor can be termed a priming pheromone because it sets in motion a chain of physiological events which, in this case, culminate in puberty. The demonstration that a social factor such as a pheromone can influence the rate of sexual development in the mouse may have implications for man. It seems likely that a complex of stimuli, certainly not odors alone, may have contributed to the accelerated rate of human sexual maturation which has occurred during the past century.